High temperature heater for fluids

ABSTRACT

Spaced burners along the roof and floor portions of a heater provide both upward and downward flows of flame and hot combustion gases to both sides of centrally positioned fluid conduits to give high temperature equiflux radiant heating to one or more fluid streams passing through the conduits. Hot flue gases are withdrawn from the mid-height wall zones of the heating chamber and are passed to a convection heating zone where additional conduits pass one or more fluid streams in heat exchange with the hot gases prior to their discharge from the heater unit.

United States Patent 1 1 1111 3,841,274 Barnes Oct. 15, 1974 [54] HIGH TEMPERATURE HEATER FOR 3,405,691 10/1968 Wallace et al... 122/356 X FLUIDS 3,476,519 11/1969 Decaux 122/356 X [75] Inventor: Marlon W. Barnes, Glenview, [11. Primary Examiner Kenneth w. p g [73] Assignee: Universal Oil Products Company, Attorney, Agent, or Firm-James R. Hoatson, J r.;

Des Plaines, lll. Philip T. Liggett; William H. Page ll [22] Filed: Nov. 29, 1973 1211 Appl. N6; 420,335 [57] ABSTRACT Spaced burners along the roof and floor portions of a I heater provide both upward and downward flows of 122/ 22/240 flame and hot combustion gases to both sides of cenn positioned fluid nduits to give high tempera- [58] Fleld of Search" 122,333 240 240 ture equiflux radiant heating to one or more fluid 22/240 B streams passing through the conduits. Hot flue gases 6 f are withdrawn from the mid-height wall zones of the 1 Re erences C'ted heating chamber and are passed to a convection heat- UNITED STATES PAT S ing zone where additional conduits pass one or more 2,625,140 1/1953 Weir 122/356 x fl id st eams in h at exchange with the hot gases prior 3,002,505 10/1961 Fleischer.... 122/240 to their discharge from the heater unit. 3,230,052 1/1966 Lee et al 122/356 x 3,385,269 5/1968 Breckenridge 122/356 x 5 Chums, 5 Drawlflg Flgures PATENIED BUT I 51974 Figure 1' Radiant Heating Zone HHHHHHHGI HHHI U Stac/r (23) Convecl/on Heal/0g Section 33 gure Figure 3 HIGH TEMPERATURE HEATER FOR FLUIDS The present invention relates to an improved heater design which is particularly useful in providing high temperature pyrolysis for fluid streams. More particularly, the present design is of advantage for providing uniform high temperature equiflux radiant heating to centrally positioned fluid conduits by having spaced top and bottom burner means firing toward the middle of the heating zone and by further having flue gas outlet means from the mid wall portions of the heater.

It is realized that radiant heating to the opposing sides of centrally positioned tubing (which type of heating is frequently referred to as equiflux heating) is not new for high temperature fluid heating. For example, reference may be made to US. Pat. No. 2,212,526, issued to L. A. Mekler, which teaches this type of heating through the use of downfired burners from the heater roof and downdraft flow of flue gases through a bottom convection heating section. Also, equiflux type of heating has been provided from the use of various types of wall burners such as a plurality of ceramic cup burners that are spaced over each side wall portion of a heating chamber, as indicated in the US. Pat. No. 2,638,879. However, in connection with these prior art heater designs, the combustion gas flows were typically upward through the top of the heating zones to convection heating sections, as updraft heaters, or downwardly to lower convection sections as downdraft heaters. With regard to the use of spaced cup burner means for providing equiflux heating, it should also be pointed out that these types of burners are limited to the use of only gaseous fuels that burn against each ceramic cup to provide substantially flameless radiant heat that is in turn radiated outwardly to the central portion of the heating zone.

In any event, it may be considered a principal object of the present invention to provide an improved equiflux heating system to permit the use of either gaseous fuel or oil or both fuels simultaneously to burners positioned at both roof and floor burner locations.

It is also an object of the present design to provide for the withdrawal of the hot combustion gases from intermediate wall portions of the heating zone, rather than from a top or bottom area, such that there can be controlled heating to both the top and bottom portions of vertically oriented fluid conduits or vertical reactor tubes, or even to both the bottom and top rows of centrally positioned horizontal tubing.

In view of the use of both top and bottom burners and the provision of equiflux type of heating, it may be reiterated that the present heater design is primarily for high temperature pyrolysis operations. However, it is not intended to limit the improved heater usage to any one type of fluid heating or to any one particular process. For example, in the petroleum processing field, the heater could well be used for high temperature thermal reforming of gas oils, high temperature soaking operations, ehtylene production, etc. The heater may also be used to advantage for the passage of steam and methane through catalyst filled tubes in a steammethane hydrogen producing operation. In other words, these suggested reactions and operations are to be illustrative of possible heater usages and not in any way limiting.

In a broad aspect, the present invention provides a heater system for one or more fluid streams, which comprises in combination, a confined radiant heating chamber for accommodating high temperature combustion gases, a plurality of tubular fluid conduits supported throughout the central portion of said heating chamber, fluid inlet and fluid outlet means for said fluid conduits, spaced burner means along the top and bottom portions of said heating chamber that project both downward and upward streams of flame and hot combustion gases to each side of said fluid conduits and thereby impart high temperature radiant heating thereto in an equiflux manner, and flue gas outlet means from the generally mid-height portions of wall sections of said radiant heating chamber that are suitable to effect the uniform removal of hot flue gases from the heating chamber.

A preferred heating system will also provide means for collecting the hot combustion gases or flue gas from the radiant heating section and passing them through a confined convection heating section whereby there may be additional heat extracted by way of one or more fluid tube banks maintained therein and prior to the discharge of the flue gases through stack means to the atmosphere. Where the stack is to be used for a natural draft operation, then the stack will be of such height as to maintain a draft or stack action for all of the flue gases being withdrawn from the central wall portions of the radiant heating section and effect a substantially uniform discharge of such gases therefrom. However, there may be a forced or induced draft in conjunction with the heater to reduce the stack height. A forced introduction of preheated combustion air can increase the flame temperature and the level of radiant heat transmission.

With respect to the top and bottom burner means, it is contemplated, as hereinbefore noted, that either gas or oil may be utilized as fuel to provide the high temperature flame and combustion gases to the radiant heating section which will in turn supply equiflux heating to centrally positioned fluid conduits. However, various types and forms of burner means may be employed and where desired the burner means may direct the hot flame and combustion gases against refractory side wall portions of the heater such that there is high temperature radiant heat from the refractory walls of the heater.

Also, as will hereinafter be described in more detail, there may be various types of tubing or fluid conduit arrangements within the present form of heater such that various types of heating operations may be carried out. For instance, there may be continuous serpentine flow through a plurality of either vertically or horizontally disposed tubular members or a parallel fluid flow between upper and lower header means. In another instance, there may be a pair of headers above or below the heating section and spaced U-tube members either hung or supported within the central heating zone to be exposed to high temperature radiant heat. In still another instance, there may be a plurality of parallel vertically supported reactor tubes adapted to contain subdivided catalyst and accommodate a fluid or vapor flow therethrough for a high temperature conversion, such as may be embodied in a steam-methane hydrogen producing system.

Reference to the accompanying drawing and the following description thereof will serve to illustrate the present improved form of heater as well as indicate certain modifications which may be made in connection therewith.

FIG. 1 of the drawing is a diagrammatic plan view of the present improved heater arrangement indicating a radiant heating section and a separate convection heating section, with the latter being generally transverse to the longitudinal axis of the radiant heating section.

FIG. 2 of the drawing is a sectional elevational view through the radiant heating section of the heater, as indicated by the line 2-2 in FIG. 1.

FIG. 3 of the drawing is a partial longitudinal elevational view which shows a portion of the radiant heating section and a cross-section through the transverse convection heating section.

FIGS. 4 and 5 of the drawing indicate, respectively, an optional fluid conduit arrangement and an elevational view of one of a plurality of tubular form reactor means which may be subjected to equiflux type of heating within the radiant heating zone of the heater systern.

Referring now particularly to FIGS. 1, 2 and 3 of the drawing, there is indicated a generally rectangular form closed radiant heating chamber 1 having side wall portions 2 and 3 as well as end wall portions 4 and 5 to define, along with a roof section 6 and bottom section 7, a confined radiant heating zone 8. As best shown in FIGS. 2 and 3, roof section 6 is provided with a plurality of spaced burner means 9 while the lower floor section 7 is provided with a plurality of spaced burner means 10. The burner means are, in each instance, provided with suitable fuel inlet piping and control valve means indicated respectively as 11 and 11'. There are also indicated, in each instance, suitable burner block means 12 to accommodate the burners 9 and through which high temperature flame may be introduced into the interior of the radiant heating section 8.

The present drawing also indicates that the radiant heating section 8 is entirely lined with a suitable high temperature resistant insulating material 13; however, where desired, wall portions 2 and 3 may be lined with high temperature resistant fire brick or refractory liner means which can sustain the impingement of high temperature flame from the respective burners 9 and 10 in the event that it is desired to direct the high temperature flame and combustion gases against the side wall portions of the heater and provide high temperature glowing radiant heat from the wall section to centrally positioned fluid conduit members such as 14.

The conduit means 14 is indicated as being of one continuous tube or conduit effecting a serpentine fluid flow and is supported in the generally vertical arrangement by suitable hanger means 15; however, as will hereinafter be set forth, various other types of tubes or conduit configurations may be utilized within the present equiflux heating system.

In accordance with the present invention, it will be noted that side wall portions 2 and 3 are provided with suitable openings at 16 to connect with flue gas outlet ducts 17 and 18 such that there is a mid point withdrawal of high temperature combustion gases with respect to the radiant heating zone 8 and resulting uniform heating to both sides of centrally positioned conduit means such as 14. Also, as best shown in FIGS. 1 and 3 of the drawing, the flue gas duct means 17 and 18 connect with opposing end portions of a convection heater section 19 defined by insulated side wall por tions 20 and 21 as well as a floor portion 22. Thus, as indicated in FIG. 3, there is a lateral and upward flow through the interior of convection heating chamber 19 to a superposed stack 23 which will have a height suitable to create adequate draft through the interior of convection heater 19 as well as uniformly from the entire length of radiant heating chamber 1. Within convection heater section 19, there is indicated diagrammatically the placement of a plurality of closely spaced convection heating tubes in a bank 24 such that there may be a heat exchange relationship with the high temperature flue gases from the radiant heating zone and the cooling of such gases prior to their discharge through stack means 23. While FIG. 3 indicates a single convection tube bank 24,it is to be noted that more than one tube bank may be accommodated by the convection heating section to, in turn, accommodate a plurality of fluid streams and it is not intended to limit the present heating system to any predetermined number of tubes or tube banks or to any one sized tubing.

Although FIGS. 1 and 3 of the drawing indicate the use of a single convection heating zone at one end of the radiant heating section, it is to be noted that additional convection heating sections may be provided in the system, as for example by having a second convection heater means at the opposing end of the radiant heating chamber 1. In this case, the flue duct means 17 and 18 could transfer flue gas flow in opposing directions to separate convection sections and to two separate stack means. Alternatively, even with separate convection heating sections accommodating a plurality of separate convection heating tube banks, there may be the overhead juncture of flue gas outlets from top portions of the convection heating chambers such that a single stack is provided for the entire heating system. In still another arrangement, there can be two or more spaced radiant heating chambers and a common convection section positioned therebetween to accommodate the hot flue gas streams.

With respect to the radiantly heated fluid stream(s), there may be as hereinbefore noted, the provision of a parallel flow through spaced tubes by having header means above and below the heating section 1 or, alternatively, parallel flow through horizontally positioned tubes by having vertical headers at each end of the radiant heating section. In still another arrangement, as best indicated diagrammatically in FIG. 4 of the drawing, there may be dual parallel headers either above or below the heating chamber such as 25 and 26 and a plurality of vertically positioned U-tube members 27 provided for central positioning within the radiant heating section 8, in lieu of the conduit means 14. As

I long as the vertically positioned U-tube members 27 are in a staggered arrangement, such as shown in the plan view of FIG. 4, there can be suitable substantially uniform equiflux heating to each side of each vertical portion of each U-tube section from the heat input to each side of the tubular members from the separate rows of upper and lower burner means 9 and 10.

In still another processing operation, such as the steam-methane production of hydrogen over suitable subdivided catalyst particles at a high temperature of the order of l,600 F., or higher, there may be utilized a plurality of vertically spaced tubular reactors 28 such as shown in FIG. 5 of the drawing. Each reactor tube 28 may, for example, contain suitable subdivided and supported nickel catalyst which is introduced into the interior of the tube by way of inlet means 29. There is also indicated the utilization of an upper header means 30 suitable to introduce the steam-methane mixture through a plurality of inlet tubes 31 into the tubular reactor means 28 whereby reaction products may be withdrawn by way of tubes 32 and header means 33. Respective upper and lower flanged connection means at 34 and 35 provide means for installing or changing reactor tubes 28 as well as providing means for withdrawing catalyst when deemed necessary. in any event, the arrangement of FIG. 5 is merely diagrammatic and illustrative of the use of a plurality of reactor tubes within the central portion of the radiant heating section 8 of heating chamber 1 in lieu of other arrangements of tubes or fluid conduit means that can provide for the equiflux heating of a particular fluid stream.

Also, it may be noted that the present drawing is merely diagrammatic with respect to the structural or construction aspects of the various portions of the heater chambers, in that supporting columns, beams, or girders, etc., have not been shown. Also, the showing of the refractory insulation means is merely diagrammatic and should in no way be considered limiting with respect to the present improved heater design which is particularly adapted to utilize both top and bottom burner arrangements and the mid zone withdrawal of hot combustion gases from the radiant heating section. Various modifications in construction and arrangement will be obvious to those familiar with high temperature heaters and, in addition, still further flue duct arrangements and convection heating section arrangements may be provided over and above those heretofore described as alternatives.

I claim as my invention:

1. A heater system for a fluid stream which comprises in combination, a confined radiant heating chamber for accommodating high temperature combustion gases, a plurality of tubular fluid conduits supported substantially vertically throughout the central portion of said heating chamber, fluid inlet and fluid outlet means for said fluid conduits, spaced burner means along the top and bottom portions of said heating chamber that project both downward and upward streams of flame and hot combustion gases to each side of said fluid conduits and thereby impart high temperature radiant heating thereto in an equiflux manner, and flue gas outlet means from the intermediate portions of wall sections of said radiant heating chamber that are suitable to effect the uniform removal of hot flue gases from the heating chamber.

2. The heater system of claim 1 further characterized in that said flue gas outlet means from said radiant heating chamber connect with at least one convection heating chamber, with the latter having a plurality of tubular-form conduit means to, in turn, accommodate one or more fluid streams to extract heat from flue gases passing through the convection heating chamber, and superposed stack means connective with said convection heating chamber providing for the discharge of resulting flue gases from the heater system.

3. The heater system of claim 2 still further characterized in that said convection heating chamber is positioned at one end of said radiant heating chamber and is oriented generally transverse to the longitudinal axis thereof, said flue gas outlet means from the mid-height portion of wall sections of said radiant heating chamber connect to both end portions of said convection heating chamber, and stack means connect with the central top portion of the latter chamber whereby flue gases are drawn both upwardly and downwardly through the radiant heating chamber and the convection heating chamber in a uniform flow.

4. The heater system of claim 1 further characterized in that fluid headers are provided over the central portion of saidradiant heating chamber and a plurality of U-shaped fluid conduit means depending into the central portion of said chamber connect between said headers to provide a plurality of parallel flow fluid stream heating means within said central radiant heating portion of said heating chamber.

5. The heater system of claim 1 further characterized in that a fluid header means extends over the roof portion of said heating chamber, an additional header means extend under the floor portion thereof, and a plurality of spaced substantially vertically positioned conduit means extending between said header means and within the central portion of said heating chamber,

whereby to provide for the equiflux heating of at least one fluid stream passing through said conduit means. 

1. A heater system for a fluid stream which comprises in combination, a confined radiant heating chamber for accommodating high temperature combustion gases, a plurality of tubular fluid conduits supported substantially vertically throughout the central portion of said heating chamber, fluid inlet and fluid outlet means for said fluid conduits, spaced burner means along the top and bottom portions of said heating chamber that project both downward and upward streams of flame and hot combustion gases to each side of said fluid conduits and thereby impart high temperature radiant heating thereto in an equiflux manner, and flue gas outlet means from the intermediate portions of wall sections of said radiant heating chamber that are suitable to effect the uniform removal of hot flue gases from the heating chamber.
 2. The heater system of claim 1 further characterized in that said flue gas outlet means from said radiant heating chamber connect with at least one convection heating chamber, with the latter having a plurality of tubular-form conduit means to, in turn, accommodate one or more fluid streams to extract heat from flue gases passing through the convection heating chamber, and superposed stack means connective with said convection heating chamber providing for the discharge of resulting flue gases from the heater system.
 3. The heater system of claim 2 still further characterized in that said convection heating chamber is positioned at one end of said radiant heating chamber and is oriented generally transverse to the longitudinal axis thereof, said flue gas outlet means from the mid-height portion of wall sections of said radiant heating chamber connect to both end portions of said convection heating chamber, and stack means connect with the central top portion of the latter chamber whereby flue gases are drawn both upwardly and downwardly through the radiant heating chamber and the convection heating chamber in a uniform flow.
 4. The heater system of claim 1 further characterized in that fluid headers are provided over the central portion of said radiant heating chamber and a plurality of U-shaped fluid conduit means depending into the central portion of said chamber connect between said headers to provide a plurality of parallel flow fluid stream heating means within said central radiant heating portion of said heating chamber.
 5. The heater system of claim 1 further characterized in that a fluid header means extends over the roof portion of said heating chamber, an additional header means extend under the floor portion thereof, and a plurality of spaced substantially vertically positioned conduit means extending between said header means and within the central portion of said heating chamber, whereby to provide for the equiflux heating of at least one fluid stream passing through said conduit means. 